In communication devices, such as wireless communication devices that perform short-range and long-range wireless radio communication, it has been the practice to use orthogonal signal processing techniques in which the baseband receive and transmit signals are put into format consisting of an in-phase (I) signal and quadrature-phase (Q) signal, where the Q signal is 90 degrees out of phase with respect to the I signal. Such orthogonal signal processing has the advantage of improving the dynamic range of the received and transmitted signals.
In order to achieve the performance benefits of I and Q signal processing, it is necessary to ensure that the I and Q signals are properly balanced in terms of amplitude and phase with respect to each other. That is, the phase offset relationship of the I and Q signals should be 90 degrees and the amplitudes of the I and Q signals should be substantially the same. In addition, it is desirable to remove DC offsets in the I and Q signals so that both signals vary symmetrically with respect to the same voltage, e.g., zero volts.
Most DC offset correction, amplitude compensation and phase compensation techniques heretofore known require complex (Fourier) signal processing techniques that are not practical in certain communication device platforms. What is needed is an algorithm that does not require complex computations in order to perform corrections for DC offset of I and Q signals, as well as amplitude and phase imbalance compensation between the I and Q signals.